Muffler



Sept. 20, 1938. F, E, PROCHNQW 2,131,001

MUFFLER Filed NOV. 13, 1956 I. lll

ATTO R N EYS Patented Sept. 20, 1938 L-UNrTED STATES PATENT OFFICE Buffalo Pressed Steel Company, Buffalo,

Application November 13, 1936, Serial No. 110,701

16 Claims.

This invention relates to improvements in muillers for use in connection with internal combustion engines, and more particularly to muffiers of the type in which sounds are silenced byv destructive interference.

vT he objects of this invention are to provide a muffler of this kind'in which the ow passage for the-gases through themufller is so arranged that a resonance chamber may be arranged within the flow passage. Anotherobject of the invention is to provide a muilier of this type in which all of the resonance chambers of the muiiler may be in direct communication with the flow passage for the gases. A further object of this invention is to produce a muliier of this type having means of improved construction for supporting a pair of shells one within another. Still another object of the invention is to provide a muffler of this kind with means of improved construction for forming a bottle neck connection with a 'resonance chamber. It is also an robject of this invention to provide improved means for supporting a pair of shells in correct relation to each other and to a head and simultaneously forming passages for products of combustion and other passages communicating with the resonance chamber to form a bottle neck type of resonator.

Other objects of this invention will appear from the following description and claims.

In the accompanying drawing:

Fig. 1 is a longitudinal central sectional elevation of a portion of a muliler embodying this invention.

Fig. 2 is a similar view of the remaining portion of the muffler.

Fig. 3 is a fragmentary longitudinal section thereof, on line 3 3, Fig. 4.

Figs. 4 and 5 are transverse sectional elevations thereof on lines 4 4 and 5 5, Fig. 1.

Fig. 6 is a fragmentary section on line 6-6, Fig. 1.

Fig. '1 is a fragmentary longitudinal section ony line 1 1, Fig. 1.

I represents the outer shell of the mufller, the opposite ends of which are closed by means of heads II and I2 of any usual or suitable construction, the heads shown being provided with integral outwardly extending tubular portions I4 and I to which the exhaust and tail pipes (not shown) may be connected in any suitable or usual manner. The heads are preferably also each provided with an annular shoulder I6.

In most mufllers of this type as heretofore constructed, the gases and sound waves are passed through the mutlier through the inner conduit, and the resonance chambers arein that case arranged about the exterior of the inner shell. In accordance with this invention, the gases and sound waves are conducted through the muler by means of an annular passage formed between two shells, for example, an intermediate shell I8 and an inner shell I9. The inner shell may form one or more resonance chambers, being for this purpose provided with baffles 20 secured within the inner shell, and the inner shell is also provided with the usual openings or perforations 2I of any suitable form which may be arranged as desired to produce within the inner shell high frequency resonance chambers.

InY order to support the two shells between which the annular passage for gas and sound Waves is formed in correctrelation to other parts of the muffler any suitable or desired construction may be employed. In the construction illustrated for this purpose, I have provided at opposite ends of the muffler sleeves 24 and 25 which are provided with grooves or channelspreferably extending throughout the length of the sleeves. If it is desired to support both the inner and intermediate shells by means of these sleeves, the depth of the grooves may be such that the inner portions of the sleeves 24 and 25 bear against the outer surface of the inner shell I9 and the outer portions of the sleeves bear against the inner surface of the intermediate-shell I8. In this manner, one end of each of the sleeves 24 and 25 may be inserted into the space between the inner and intermediate shells and thus hold these sleeves in correct relation to each other.- 'I'he sleeves are thus provided with inwardly facing channels 21 through which the gases and sound waves may pass and which establish communication between the interior of the sleeves and the annular passage for the gases. The sleeves may be secured to the heads of the muffler in any suitable manner. Preferably the sleeves are also so proportioned with relation to the shoulders I6 of the ends of this muffler that the outer surfaces of the sleeves t snugly-against the shoulders I6, and the outer ends of the sleeves 24 and 25 abut against transverse portions of the heads II and I2. Consequently, the sleeves 24 and 25 may be readily welded to the heads II and I2 as'indicated, for example, at 28, Fig. 3, and the sleeve 24 lmay also be Welded to the inner and intermediate shells, as shown lat 29 and 30, Figs. 1,3 and 5. This forms a strong and'rigid connection between the head II and the `adjacent ends of the inner and intermediate shells. If the muiller is of considerable length, it may be preferable to provide expansion and contraction of the inner and intermediate shells relatively to the outer shell by welding one ofthe sleeves, for example, the` sleeve 25 to its head I2 but not to the inner 4and intermediate shells so that a sliding connection between thesleeve 25 and these' two shells is provided, as clearly shown in Fig. 2. If desired, to facilitate assemblyv of the head I2 and the sleeve 25 secured thereto in correct relation to the inner and intermediate shells, suitable spacing means, such as flanged thimbles 3I may be provided, the fianges 32 of which may be welded to the inner shell I9. By providing three or more of these thimbles, the inner and intermediate shells will be held in properly spaced relation toeach other so that the sleeve 25 may readily be inserted into the annular space netween these two shells.

The muffler is, also provided with suitable resonance chambers arranged about the gas passage, and in the construction illustrated, these resonance chambers are provided between the outer shell IU and the intermediate shell I8, and one or more bafiies 34 may be provided in this space. This baflie 34 as is customary in mulilers of this type may be so positioned with relation to the ends of the mutlier as to produce low frequency resonance chambers of the desired length to counteract certain Wave lengths encountered in the particular engine which the muffler is intended to silence.

It is well known that the action of the resonance chambers may be greatly modified by providing these chambers. with restricted passages or channels leading to the same to form bottle neck type of resonance chambers. This is accomplished in the muflier illustrated by means of channels 35 in the sleeves 24 and 25 which face outwardly and by having the intermediate shell I8 terminate at distances from the heads II and I2 of the muffler. These channels 35, which may be formed alternately with the channels 2l', terminate at their inner ends in the annular gas and sound wave conducting passage between the shells I8 and I9. The outer ends of the channels or ducts 35 terminate in the annular space formed between the ends of the intermediate shell I8 and the adjacent heads.

In the operation of the muffler described, if the tubular extension I4 of the head II of the muffler is` connected with the exhaust pipe of an engine, the exhaust enters in the sleeve 24 and passes through the channels 21 therein into the annular gas conducting passage between the shells I8 and I9. High frequency sound waves enter into the inner resonance chambers within the inner shell I9 through the perforations 2l in the shell and return into the annular passage out of phase with corresponding sound waves, which are thus silenced by destructive interference. Low frequency sound Waves from the annular gas passage pass through the channels 35 into the outer resonance chambers. At the discharge end of the mufller, the gases and sound waves pass through the channels 2liof the sleeve 25 into the interior of this sleeve beyond the end of the inner shell I9, and are discharged through the tubular extension I5.

It will be noted that by means of this construction, low frequency sound waves pass di rectly from the annular gas conducting space into the bottle necks or passages 35 of the low frequency resonance chambers, thus eliminating the need for intermediate chambers heretofore required to transmit low frequency sound Waves from the inner shell to the bottle necks. In adapting mufilers of this kind to eliminate particular sound waves of an engine, it is possible not only to change the position of the baffle 34 to .adapt the outer resonance chamber to the silencing of the sound waves encountered in the engine but the bottle necks formed by the passages 35 can also be varied by varying the lengths of the sleeves 24 and 25. The high frequency resonance chambers in the inner shell I9 may also be modified by the location `and number of the perforations 2| and by the location of the baiiies 20 within this shell. By locating the passage for the gases nearer to the outer surface of the muffler, a more rapid dissipation of heat through the outer shell of the muffler results.

I claim as my invention:

1. A muiiier having an inner perforate shell having its end portions closed to form therein an inner resonator Chamber, an intermediate shell arranged about said inner shell and forming therewith a passage for gases and sound waves, an outer shell surrounding said intermediate shell and forming therewith an outer resonator chamber, communicating with said passage and means extending transversely of said outer resonator chamber to substantially interrupt the passage of gases therethrough.

2. A muliier having a shell forming a passage for gases and sound waves through said muffler, a perforate inner shell arranged within said first mentioned shell and having an end thereof closed and forming a resonance chamber into which sound waves may enter through the perforations therein, an outer shell arranged about said first shell and forming therewith outer resonance chambers connected with said passage,

3. A muffler having a shell forming a passage for gases and sound waves through said muffler, a perforate inner shell arranged within said first mentioned shell, a transverse wall in said inner shell forming a resonance chamber into which sound waves may enter through the perforations therein, an outer shell arranged about said first shell, heads closing the ends of said outer shell, said first shell and said outer shell forming between them an outer resonance chamber, and means for spacing said first and inner shells relatively to each other .and forming elongated channels of smaller cross sectional area than said outer resonance chamber and connecting said outer resonance chamber with said passage.

4. A muflier having a shell forming a passage for gases and sound waves through said muffler, an inner shell arranged within said first mentioned shell, a transverse wall in said inner shell forming high frequency resonance chambers communicating with said passage, and an outer shell arranged about said first shell and forming therewith a low frequency resonance chamber communicating with said passage.

5, A muffler having a shell forming a passage for gases, a second shell arranged within said first shell, a plurality of transverse baflies within said second shell and dividing said second shell into a plurality of resonance chambers, said second shell also having openings which establish communication between said passage and said chambers and through which sound waves may pass.

6, A muffier having a shell forming a passage for gases, a second shell arranged within said first shell and having a plurality of transverse baflies dividing said second shell into a plurality of resonance chambers, said second shell also having openings which establish communication between said passage and said chambers and through which sound waves may pass, and an outer shell arranged about said first shell and forming therewith a chamber which communicates with the interior of said rst shell.

'7. A muffler having a shell through which gases may pass, a second shell arranged within said first shell and Ihaving a plurality of transverse bailles dividing said second shell into a plurality of resonance chambers, said second shell also having openings which establish I,communication between said passage and said chambers and through which sound waves may pass, an outer shell arranged about said rst shell and forming therewith a chamber which communicates with the interior of said first shell, and a sheet metal member arranged between said first and second shells and having a channel extending from the interior of said first shell to said chamber between said first and outer shells to form a bottle neck therefor.

8. A muffler having a shell forming a passage for gases and sound waves, a perforate shell arranged within said first shell and divided into a plurality of chambers into which sound waves may enter from said passage through the perforations of the inner shell, an outer shell arranged about said first shell and forming therewith a resonance chamber, and a channel-shaped member arranged between said second shell and said first shell for forming a bottle neck for said resonance chamber and communicating at one end thereof with said chamber and at the other end with the passage within said first shell.

9. A muffler having a. shell forming a passage for gases and sound waves, a shell arranged within said first shell and forming therewitha passage for gases and sound waves, said inner shell communicating with said passage to destroy sounds in said passage by destructive interference, an outer shell arranged about said first shell and forming therewith a resonance chamber, and means cooperating with said flrst shell and forming therewith an elongated channel of materially less cross sectional area than said resonance chamber and connecting said passage with said resonance chamber to form a bottle neck resonance chamber.

10. A mufller including a pair of shells arranged one within the other and forming between them a passage for gases and sound waves, the inner of said shells being perforate, means for dividing said inner shell into a series of resonance chambers into which sound waves may enter through the perforations of said inner shell, a sleeve extending between said shells and provided with a series of longitudinally extending grooves which form channels connecting the interior of said sleeve with the space between said shells.

11. A mulller having inner, outer and intermediate shells arranged one within another, the inner of said shells being perforate, means for dividing said inner shell into a series of resonance chambers, and a sleeve extending between said inner and intermediate shells and provided with longitudinally extending inwardly and outwardly facing channels, the inwardly facing channels conducting gases and sound waves from the interior of said sleeve into the space between said inner and intermediate shells, and the outwardly facing channels forming bottle necks communicating with the space between said inner and intermediate shells and with the space between said intermediate and outer shells to form with said last mentioned space a bottle neck resonator.

12. A muffler having inner, outer and intermediate shells arranged one within another, the inner of said shells being perforate,l means for dividing said inner shell into a series of resonance chambers, heads closing the ends of said outer shell, and a sleeve secured at one end to one of said heads and arranged in spaced relation to the intermediate shell and forming therewith a bottle neck passage connecting the space between said inner and intermediate shells with the space between said intermediate and outer shells.

13. A mufller having inner, outer and intermediate shells arranged one within another, the inner of said shells being perforate, means for dividing said inner shell into a series 0f resonance chambers, heads closing the ends of said outer shell, and a sleeve secured at one end to one of said heads and supporting said inner and intermediate shells in fixed relation to said head, said sleeve having portions thereof spaced from said intermediate shell to form therewith bottle neck channels connecting the space between said intermediate and outer shells with the space within said intermediate shell.

14. A muffler having inner, intermediate and outer shells arranged one within the other, said inner and intermediate shells being spaced from each other to formv between them a passage for gases and sound waves, and said inner shell being perforate, means for dividing said inner shell into resonance chambers communicating with said passage, heads closing the ends of said outer shell, and a sleeve formed into a series of inwardly and outwardly facing and longitudinally extending channels and secured at one end to one of said heads and terminating at its other end in the space between said inner and intermediate shells, the inwardly facing channels ol' said sleeve serving to conduct gases and sound waves from the interior of said sleeve to said passage, and the outwardly facing channels forming bottle necks connecting said passage with a resonance chamber formed between said outer i and intermediate shells.

15. A muler having inner, outer and intermediate shells, the inner shell being arranged within said intermediate shell and the intermediate shell being arranged within said outer shell, heads at the opposite ends of said outer shell, means spacing said inner and intermediate shells from each other and from said heads, to form a passage through said mufller from one head to the other in the space between said intermediate and inner shells, said inner shell having baflles therein forming a chamber in said inner shell and having perforations through which sound waves from said passage may enter said chamber, the space between said intermediate and outer shells also communicating with said passage and forming resonance chambers.

16. A muler having inner, intermediate and outer shells, the inner shell being arranged within said intermediate shell and the intermediate shell being arranged within said outer shell, means cooperating with said shells to form a passage for gases and sound Waves between said inner and intermediate shells, means extending transversely of said inner shell for forming within said inner shell a resonator chamber communicating with said passage, and transversely extending means for forming a resonator chamber between said intermediate and outer shells and communicating with said passage.

FELIX E. PROCHNOW. 

